As embodiment of electrically powered light source, an LED is a relatively recent development since the incandescent lamp and the gas discharge lamp. Although LEDs are known for use as indicator for a relatively long time, typically as POWER ON indicator in a consumer appliance, a rather recent development is the use as illumination light source, which became possible with the development of power LEDs. LEDs are nowadays used for ambiance lighting, for signaling (traffic lights and the like), and even for tail lights, brake lights and head lights of automobiles.